Miscellaneous

Why do I get the error: module 'websockets' has no attribute '...'?

Often, this is because you created a script called websockets.py in your current working directory. Then import websockets imports this module instead of the websockets library.

Why does my IDE fail to show documentation for websockets APIs?

You are probably using the convenience imports e.g.:

import websockets

websockets.connect(...)
websockets.serve(...)

This is incompatible with static code analysis. It may break auto-completion and contextual documentation in IDEs, type checking with mypy, etc.

Instead, use the real import paths e.g.:

import websockets.client
import websockets.server

websockets.client.connect(...)
websockets.server.serve(...)

Why is websockets slower than another Python library in my benchmark?

Not all libraries are as feature-complete as websockets. For a fair benchmark, you should disable features that the other library doesn’t provide. Typically, you may need to disable:

• Compression: set compression=None

• Keepalive: set ping_interval=None

• UTF-8 decoding: send bytes rather than str

If websockets is still slower than another Python library, please file a bug.

Can I use websockets without async and await?

No, there is no convenient way to do this. You should use another library.

Are there onopen, onmessage, onerror, and onclose callbacks?

No, there aren’t.

websockets provides high-level, coroutine-based APIs. Compared to callbacks, coroutines make it easier to manage control flow in concurrent code.

If you prefer callback-based APIs, you should use another library.